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The optical and bactericidal properties of acetic and basic chitosan films were studied. By the ORD technique, we found that these films differed in the values of their specific optical rotation[α]and of their rotary and dispersive constants. A sign inversion of[α]was observed when the acetic chitosan films were heat-treated. The bactericidal activity of the initial and dehydrated acetic films was analyzed, and their moisture content and optical and biological activities were compared.

A microelemental, thermal, and IR spectroscopic analysis of samples of chitosan separated from fresh-and salt-water crustaceans was performed. The viscometric and optical properties of the solutions made from them freshly prepared and during storage were investigated. It was found that the physicochemical characteristics of crayfish shell chitosan almost do not differ from the indexes for the industrial polymer prepared from a traditional source of raw material crab shells. This allows considering crayfish shells as an alternative raw material resource for obtaining chitosan.The natural polysaccharide chitosan (CTS) is used in the chemical, cosmetics, and food industries, in agriculture, and in human and veterinary medicine [1][2][3]. Commercial marine crustacean shells are the basic raw material source in industrial production of CTS. In view of the cost and uniqueness of this product and the enormous area of practical application, searching for different accessible resources capable of ensuring wide production of CTS is pressing.For regions distant from the sea, this problem can be solved by using objects from our own industry, for example, crayfish shells. Not only will the raw material base for CTS technology expand significantly, but the cost of the final product will decrease significantly. The possibility of obtaining chitin and CTS from crayfish shells was reported earlier [4][5][6][7]. A comparative analysis of the physicochemical properties of CTS obtained from different raw-material sources is reported here: salt-water crab and fresh-water crayfish shells.Samples of CTS obtained from crab shells (CrS) in industrial conditions at Bioprogress AOZT and from crayfish shells (CS) in laboratory conditions with our technology [5] and from solutions and films were investigated. The samples are characterized in Table 1.The samples of CTS investigated had a similar degree of deacetylation, almost did not differ in molecular mass (except for CTS-1), and did not dissolve in distilled water.The viscosity-average molecular weight of the polysaccharide was determined viscometrically by the standard method and calculated with the MarkKuhnHouwink equation with the constants from [8]. The viscosity was measured in a Ubbelohde viscometer with a 0.54-mm capillary diameter at 25°C. Solutions of 0.05 and 0.5 g/dl concentration were prepared by dissolving a weighed portion of polymer powder in CH 3 COOH (0.33 mole) + CH 3 COONa (0.2 mole) acetate buffer for several days. Cp glacial acetic acid and sodium acetate were used. The degree of deacetylation of the samples was determined by potentiometric titration.The optical rotation spectra of the CTS solutions were made on a SPU-E automatic spectropolarimeter in the wavelength range of λ = 300-710 nm at t = 25°C. A high-pressure DRSh-250 mercury lamp was the light source. Glass thermostated cuvettes 1 dm long with quartz windows were used. The specific optical rotation [α] was determined according to the recommendations in [9]. The concentration of the solutions was 0.2-0.5 g/dl...